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United States Department of Agriculture

Agricultural Research Service

Title: Effect of Fungicidal Spray Program on Resveratrol Production of Muscadine Grapes (Vitis Rotundifolia MICHX.)

Authors
item Magee, James
item Smith, Barbara
item Rimando, Agnes

Submitted to: HortScience
Publication Type: Abstract Only
Publication Acceptance Date: June 5, 2000
Publication Date: June 5, 2000

Technical Abstract: Control of muscadine diseases is necessary to minimize yield loss and is especially important for highest quality if the berries are marketed fresh. In 1998 vines of five muscadine cultivars were treated under a systematic disease control spray program. Four fungicides registered for use on grapes were applied sequentially at 10 to 20 day intervals from early bloom until just before harvest. Control plants received no fungicide. The objectives of the study were to determine the effects of the spray schedule on foliage and berry diseases and the relationship between disease incidence and resveratrol content of the berries. Resveratrol, a phytoalexin, has been favorably implicated in cardiovascular disease and certain cancer processes. Foliar diseases were rated visually twice during the season. Berry disease ratings were made at harvest. All fungal foliage and berry diseases were significantly reduced by the fungicide treatments. Resveratrol was determined separately on berry skins, seed and pulp/juice by GC/MS. Overall, resveratrol levels in berry skins from unsprayed vines were much higher than those of sprayed vines. Concentrations varied by cultivar and within cultivar by treatment. The relationship of skin concentration and total disease score or scores of specific diseases was not established. Seed resveratrol concentrations differed by cultivar but were not affected by the fungicide treatments. Mean concentration of seed was lower than that of skins. Resveratrol in juice/pulp was much lower than in skins and seeds.

Last Modified: 7/22/2014